This invention relates to attachment devices mounted to the loader arms of front end loading tractors for attaching lifting or loading implements to the tractors, especially to attachment devices which do not require manual operations to secure the device to the tractor, as is oftentimes required of the tractor operator. This invention further relates to a device as described above which includes an adjusting mechanism for maintaining a securely locked relation between the attachment device and the lifting or loading implement.
The use of attachment devices is necessitated by the need for flexibility in the use of various loading devices for end loading tractors. Farm duty loaders, for example, may be required to carry loads of dirt on one occasion and bales of hay on another. To do these different jobs, different tools are required. To carry the dirt, a scoop would be the necessary implement, while for carrying bales of hay, the farmer would prefer to use forks. The problem faced when switching from one to the other is largely concerned with the fact that the implements involved are very heavy. Typically, the end loading tractor has two hinged loader arms extending therefrom, the ends of which carry the loading implements. The problem addressed by attachment devices is how to quickly and securely switch from one loading implement to another.
These attachment devices are firmly secured to the arms of the tractor as by bolts, for example. Typically, a spacing device such as a long metal bar or tube is extended between the two attachment devices in order to maintain their relative position one to another. This is because to effect easy attachment of the loading implement, the two attachment devices must be rigidly spaced from each other. Typical attachment devices are equipped with receiving means for two cross pins, a pair of which are provided in two locations on the rear of most loading implements in standard locations intended for mating with loader attachment devices. The horizontal pins are also typically spaced apart in standard spacing arrangement for attachment to various attachment means.
There are many varieties and styles of attachment devices available for use with front end loaders. Among these are those disclosed in U.S. Pat. Nos. 4,436,477, 3,985,249, 3,964,622, and 3,807,769, as well as German Pat Nos. 1,277,608 and 1,164,323. Further, Applicant has previously filed and abandoned application Ser. No 755,304 filed July 15, 1985. Many of these patents teach various methods of automatic attachment, each differing to some degree from Applicant's, but none provides a means for maintaining the securely locked relation between the attachment device and the lifting or loading implement referred to above.
U.S. Pat. No. 4,436,477 issued to Lenertz et al. on Mar. 13, 1984 shows a quick attachment assembly provided with an externally mounted locking means which requires modifications to the horizontal pin housing found on the load lifting implement. U.S. Pat. No. 3,985,249 issued to Aker et al. on Oct. 12, 1976 teaches another externally mounted locking device requiring modifications to the horizontal pin housings found on the load lifting implement. U.S. Pat. No. 3,964,622 issued to Blair et al. on June 22, 1976 shows a configuration in some ways similar to Applicant's, yet significantly different in that it provides no means for automatic attachment of the lifting implement to the attachment assembly. U.S. Pat. No. 3,807,769 issued to Thompson et al on Apr. 30, 1974, discloses a quick hitch attachment which is in fact a very complicated mechanism with several moving, pivoting parts. German Pat. No. 1,227,608 issued to Muncke on Sept. 12, 1968 shows two pivoting portions for securing the top and bottom horizontal pins in position. Finally, German Pat. No. 1,1644,323 issued to Baas on Feb. 17, 1964 shows a latching mechanism for loading mechanisms with single horizontal pin arrangements in which the pivoting portion is held in place by a vertical rod. However, the pivot point taught therein lies below the point at which the horizontal pin is secured, and Baas fails to demonstrate how such a pivoting securement may be attained with a pivot point located thereabove.
An important problem encountered in this art which is not addressed by any of the above-noted devices is the fact that the horizontal pins which reside in the slots of the attachment mechanism gradually wear away at the seating area of the slots over long periods of use. This is especially noticeable in the lower slot where, as the amount of wear increases, the horizontal pin may be free to slide about from front to back within the slot region. This loose fit condition, or chatter, if allowed to go on unchecked, continues to grow worse over time, and the security of the fit between the attachment device and the loading implement becomes suspect and vulnerable to disengagement, with the attendant risk of accidental injury or property damage.
With this background in mind, an automatic quick attaching device for front end loaders which is simple to operate and which effectively reduces chatter has been developed.